Okay, a few things here.
First, yes the Browns are a relatively 'safe' choice, but are not necessarily the best overall switch. Sure, they aren't as noisy as the Blues. Or as heavy as the Clears. So they shouldn't pose any insurmountable problems.
But, as you say, they aren't very tactile, and they are fairly light. So it may not be your preferred switch, not your 'ultimate' switch.
From Browns, it's easy to transition to other MX switches of similar weight.
Browns are basically MX Reds that have a slight tactile component. So if you get used to Browns, Reds aren't too much of a leap. And Browns are a little similar to the tactility you find in some membrane keyboards, so it's not a huge adjustment coming from those kind of boards. One of the reasons they're recommended as a 'beginner' switch.
Second, you asked about MX Clears. They are indeed a relatively weighty and highly-tactile switch. Lots of pros favour them, but I see even these enthusiasts complain about fatigue after as little as one hour.
So it's a great-feeling switch for some people, but it is relatively heavy. [There are lighter versions and clones of this switch, but they're in the enthusiast market].
If you can handle it, though, you could go straight to the Clears. They are an 'endgame' switch for plenty of users.
Third, as you said, the switch tester can be misleading. What one switch feels like is not like what an entire keyboard will feel like.
For example, with the Browns you mention, they feel pretty underwhelming as individual switches. But Cherry did not manufacture them to be used as individual switches. On a keyboard, the Browns give you just enough tactility to know that you actuated a switch, but without distracting you so much that you can't rapidly move on to the next switch. You don't type one-switch-at-a-time with MX Browns, you type one word at a time.
Browns are supposed to be an unassuming, easy-typing switch that does not have a lot of personality.
Fourth, if you are going to play around with advanced, expensive switches, it makes sense to get a cheap switch-testing board. Someone recommended the GMMK, which will work. Although, if you aren't in the U.S. and can order cheaply from China, I would get a TeamWolf Zhuque from AliExpress. It's metal-cased instead of plastic, although the RGB is inferior to the GMMK.
But you need ISO, so go with GMMK. I think they make models with ISO.
Finally, if you have a general sense of the switches from your switch sampler and plan to order one of those four keyboards, they are mostly good choices.
A family member has a Varmilo VA87, and it is amazing. Simply amazing. But it's using the new MX Browns, and not MX Clear. You'd better be sure you like MX Clear before shelling out for the VA88M. Great keyboard, heavy switch.
I don't know much about the Vortex Race 3. People speak highly of theirs, but it's a non-standard layout, which will make aftermarket keycap purchases more difficult.
The WASD keyboard is nothing special, I think it's a rebranded Costar of some sort. I certainly wouldn't pay extra for it.
The FC980M is a spectacular keyboard, and Leopold's been using good Browns recently.
It really comes down to the layout and switch. What do you want?
Advantage of the Varmilo VA88 is that it is a relatively standard layout [even though these are all ISO], so there's still lots of keycap sets you can order for it, even some of the cheap ones.
Advantage of the FC980M is the build quality [maybe the best out of your options], and even the non-standard layout is highly celebrated by its fan base.
Have you tried any of these non-standard layouts? Because that is key.
TL;DR:
1. Browns are safe for new people. Maybe not the be-all and end-all of all switches, but they are comfortably mediocre.
2. Clears are powerful tactile switches, but can be tiring even to experienced users.
3. Using switches on an actual keyboard is the only real way to get a feel for them.
4. It is very useful to get a cheap switch-testing board if you are going to be trialing a lot of different switches. Especially before an expensive purchase.
5. All four of your choices are from reputable brands. Leopold in particular is well-regarded, and I enjoy Varmilo very much. It comes down to your switch and layout preference.
