I prefer 'wet' trainers as well, but if he's already spent the money, it's hard to justify more - at least, right away.
There's gotta be a gazillion threads in the beginner's forum about 'best trainer', but: I did a seearch on 'tiger trainer'. The first thing that came up was a thread in a discussion forum with prolly 85% positive comments about it (the .40).
Sig Kadet LT40 is probably the best plane out there for training, in my opinion. Kit or ARF. Flies well on anything over a .40 and is aerobatic (pretty much) once you move the CG and hot up the control-surface throw.
All the other trainers are OK, really. Some have better workmanship or worse (if they're ARF) but they all fly, as far as I know. If you can blow the money, go with a .60, I guess. I always flew .40's - everything's a little bit cheaper. Fuel, parts, room in the car, etc. Granted, 60's are bigger and easier to see - but I had a .21 4-stroke powered oldtimer that had a 6-foot wingspan - how big a plane do you want?
All planes are cool...just match 'em to your skillset. (Notice I'm refraining from a salespitch for the BALSA USA STIK .40 PLUS....oh - my caps-lock key must've stuck