Question about 4K TVs and their refresh rates

So, Im about to buy myself one, and Im on a budget (aiming for 600€, but Im thinking of stretching for 700 for one tv that is on sale atm). I dont demand much, and I just want to future proof myself now with an alright 4K TV.

One weird thing I noticed, is that so many TVs in my region are either 50Hz, or 100hz. This seems so backwards, when few years back every fullHD TV was 60Hz at least. Im in the PAL region, but it should no longer matter at this day and age, right?

What's up with this? Are all TVs actually capable of 60Hz for gaming for example, and/or if I buy a 100Hz TV am I going to experience tearing? All of the TVs say they can accept all sorts of 50/60Hz signals.

It seems to be so hard to gather any solid info on these specs, so I though maybe somebody here would know?

The TV models that Im looking at are:

Samsung 49" 4K UHD Smart TV UE49MU6105 (600€ in sale)

Sony 49" 4K UHD Smart TV KD-49XE7096 (700€ in sale)

SAMSUNG 49" 4K HDR SMART-TV UE49MU6175 (just came into one of the stores, and it seems fine but apparently Samsung no longer discloses their refresh rates? Just barely under 600€).

One sales person claimed that even though Samsung doesnt disclose their TV's refresh rates, almost all of their mid tier 2017 models are going to be at the 100Hz standard. Any validity in this?

Help would be appreciated. I just want something that I know is not stuck bellow 60Hz. Samsung and Sony apparently have been pretty good with their game modes, and all of these models still have either composite, or component connections, which Im also satisfied with since I still do some retro gaming here and there.