Main question is do you LIKE/LOVE light tanks? I personally ADORE light tanks, so I heavily lean towards lights in my lineups/premiums. The M1 KVT is not a great tank, not bad, but really not great.
Huge diff between the Wolfpack and the M1 KVT are their best darts:
Wolfpack gets M900 with 521mm pen

M1 KVT gets M774 with "only" 371mm pen

The RDF has IRST and prox fused rounds, so you “can” lock onto air targets and lob prox rounds at them. Not saying it counters your point about being CAS spammed, but, it can at least lock and pop them. Especially Helis.
I LOVE the Wolfpack, and its Gen 3 thermals for BOTH gunner and commander cannot be overstated. ALSO, the M1128’s both have hydro pneumatic suspensions now, so you can not only lower/raise, but you can also tilt forward/back, helping with their bad gun depressions.
Another huge thing to consider is BR ratings because ALL of these are Rank VII and will grind out the entire US ground tree just as effectively (if you can get kills) but the Wolfpack sits at 10.3 BR which will prevent you from seeing any uptiers higher than 11.3 BR. (And the Wolfpack is only 9.7 BR in GAB, which is just amazing if you want to do some GAB grinding.)

US Rank VII premiums, GAB BR's

The Clickbait and the RDF/LT are 11.7 so you will almost always been in full upteirs to 12.0 ground and 12.7 air CAS (or w/e the highest CAS BR is currently.)
Also of note, the RDF/LT only has Gen 1 thermals, which for me personally, are almost useless in GRB: Ground Thermals – Thunder View
Of the Rank VII US premiums, only the Wolfpack has better than Gen 1 thermals:

I would recommend considering which BR’s you are most willing to suffer, as the M1 KVT will push you into nearly full top tier games up to 11.7 versus “almost” top tier with the Wolfpack up to 11.3
Since I am so strongly biased towards light tanks, I would recommend the Wolfpack, but you need to decide for yourself how much you like light tanks versus MBTs. The Wolfpack is an excellent vehicle, but you can NOT run face first into fights or you will get annihilated nearly instantly every time. But with its Gen 3+3 thermals, you can use the commander sights and see up over most hills and scout with the superb Gen 3 thermals (just in case you didn’t know too: you can not only scout in Commander sight, but use your laser rangefinder too. And fire from Commander sight if you turn on Commander Fire Control, with its associated keybind.)
Finally, the Wolfpack also has a crewless turret, so if you are careful, you can often avoid being one shot when you peak up over hills to scout and/or fire (HE/HEAT/Rockets will still probably one shot you from overpressure, but with most people running darts at those BR’s, it doesn’t happen that often. Spalling from autocannons from BMDs/BMPs/2S38s etc can sometimes get down into your ammo rack, so be a little careful with those.)
If you are 100% deadset on buying one of the on sale US premiums though, I would go with the RDF/LT. But I have to repeat myself, that I am extremely biased towards using light tanks. So, I would prefer to suffer the 11.7 → 12.7 uptiers rather than use a premium MBT to grind out a tech tree.
EDIT #1:
You should deeply consider this about light tanks ☝️ NO armor, especially with the Wolfpack. (I do not have the RDF/LT, so cannot speak on its “armor”.) Many players do not like how squishy light tanks are. I am almost certainly in the minority for liking light tanks so much.