Viltrumite (Invincible) vs Saiyan (Dragonball), full deep dive:

So it's obvious that this has been going on for awhile, with angry yelling on both sides, so I decided to make this, and cover every aspect I have found about this subject:

(Note: the sample size for this comparison is VERY SMALL on both ends.)

Strength:

• Saiyans possess superhuman lifting strength across the board, with feats such as Goku lifting an entire tractor and casually flying off with it, or Goku being able to fight with several tons on each limb. However, as we will talk about more later, their lifting strength is far surpassed by their actual damage output. Great ape is a 10x power boost, but I'm willing to argue that the actual physical lifting strength likely goes up past 10x but that's only speculation.
• Viltrumites are a bit harder to calc... but it's clear they surpass saiyans fairly easily in this catagory, Mark Grayson, a half viltrumite, was able to keep a large building from falling down, and even though it did eventually collapse it was not because of any failure of Mark, but simply because the building itself was unstable... mark by this point had not gone through any major training and was still considered quite weak by viltrumite standards. And a quite weak viltrumite comes out to tens possibly hundreds of times stronger than base goku.
• In terms of lifting strength this is an easy win for the viltrumites.

Speed:

• Saiyans cannot fly fast... sure they fly faster than jets and stuff but for the comparison we are making here, it still takes several minutes to fly to different locations within the same country! That is not to say that they have slower reaction times though... Saiyans fight with blows being shared at speeds so fast you don't even see them move! Saiyans can pilot FTL pods and even dodge meteors while flying on FTL ships! They could theoretically travel at these speeds, but there's likely a stamina issue, like a sprint taking too much effort to be sustainable.
• Viltrumites have inconsistent reaction but proven FTL capabilities! The simple fact is that in order to fly at MFTL speeds you need to be able to react at MFTL speeds... however it's stated in the guidebook that Alan the Alien, (Someone made in the image of viltrumites to fight them), actually has reaction time scaled to how fast he's moving. Though we have no proof this is how it works for viltrumites, it would make sense given Alan was made to mimic and fight them, as well as the inconsistent reaction times when either not moving or moving slowly. They are capable of moving FTL+ within an atmosphere, however the guidebook states directly that they do not as it would cause irreparable damage to the planet in question.
• In terms of applicable speed this goes to the Saiyans as they aren't likely to be moving too far while fighting.

Durability:

• Saiyans possess Ki, which boosts every aspect of their body, acting as a shield, a beam, and a force multiplier. While they can still get punched by powerful opponents ki essentially acts as armor, capable of tanking Moon to even multi planet level blows. There are notable weaknesses though: Primarily Ki does not appear to protect them from raw heat, as not only are they hurt by elements like lava, but while escaping Buu Goku and Vegeta complained and were even worried that the steam within Buu could kill them with it's heat. There is also the weakness of their tail, as it is far more sensitive than the rest of their anatomy, and can be grabbed to inflict great pain... however this weakness can be trained out of a Saiyans system, and several methods have been found attempting to remove this as an exploitable weakness, including... tying it up as a belt, or just straight up cutting it off.
• Viltrumite's bodies are composed of smart atoms, and what they do is adjust to change the form and function of the rest of the body, this works both offensively and defensively as it makes sure they can tank punches from their fellow viltrumites, as well it makes a viltrumite capable of making just their hand so durable it can be used to literally cut through other viltrumites! There are weaknesses however: Namely it is a proven and consistent factor that extreme temperatures destabilize viltrumites, such as when powerplex killed a mark variant with his lightning powers, or the danger of the Viltrum feat being amplified by the high and plasmic heats within the planet itself, of the fact that a Season 3 mark grayson could tank a solar flare causing nuke, but couldn't stay under lava for more than 7 minutes before pulling out. Their ears are also highly sensitive, as well as very important, as they allow viltrumites to maintain their equilibrium while flying! As for how strong their durability is outside these specific conditions... that's a bit tough to discern. We have seen directly however that characters such as the universe destroying omnipotus, or the mighty supreme have severe issue harming viltrumites! However, a more solid feat is looking at the weapons of those who were actively losing to them. The Coalition of planets had been fighting the viltrumites for decades, and had weapons, and tools, and Alan helping them... yet despite the fact that their weapons are capable of anywhere between planetary to a star level yield, their best bet was Alan... who until the events of the story proper, could not defeat even a single viltrumite in combat!
• Overall in terms of durability I'd put this at about equal... though saiyans have more explicit showings of surviving more powerful blasts, it is noteworthy that they have very easily exploitable weaknesses as well as we know that they can't be throwing out planet busting punches every time they punch... otherwise they'd be doing a lot more damage to the enviorment around them. Whereas viltrumites do not possess the same immediate weaknesses but also have far less explicit showings.

Attack and Versatility:

• Saiyans possess not only long ranged capabilities but also telekinesis if ki is applied correctly! Whereas though the average viltrumite is a better fighter... they are very limited by the fact they need to fly in close to land their big punches, which is highly dangerous in the long run given the fact that a saiyans ki blasts likely produce heat, which could soften or damage a viltrumite's body, or in the case of a massive blast... perhaps even kill the viltrumite outright! In this catagoty it has to go to the saiyans simply for their ability to deal massive damage from a safe distance

Resistances:

• Viltrumites win this easily... everything the saiyans can survive in the viltrumites can do 10 times better, just as well viltrumites can also survive in the vaccum of space, as well as hold their breath for longer underwater and survive in extreme heat for longer as well. However what is noteworthy is that unlike a viltrumite's sensitive hearing... Saiyans can actually train to eliminate their tail as a weakness!

Endurance:

• Viltrumites can fly for months without sleep and fight for weeks while heavily injured... Saiyans have a limited pool of ki that gets lower the longer they fight... Viltrumites win.