I have a G27, drove the G29 and the DFGT, also the T300 in a store.
I drive my own car ('95 C-Class) everyday and did a trackday-training with spinning out etc. with it. Drove 20+ different cars (mum, dad, friends, car sharing etc.) and I am a very "technical" person.
That said I will be brutally honest:
Please don't buy either of them!
The G29 has more or less the same motor, ffb etc. as the G27 and if you don't like to spend many hours for tweaking for the right settings I can't recommend it!
The problem is the huge deadzone in the center position. It's to stop the wheel from shaking on straights but in reality you lose feeling in every single game on straights and turning in is a problem because you get a massive "force bump" after a few degrees. The T150 has more or less the same "response curve" and therefore the same deadzone
Here are a few Links for you to understand better:
G27ResponseCurve
T150ResponseCurve
MyMiniDemoOfTheDeadzoneYoutube
and finally my guide for Assetto Corsa to let you see what you would have to do to get a GOOD feeling in a Sim:
LINK
The T300/500 are a bit better, smoother overall and don't have a deadzone THAT big! The Fanatecs and even better wheels don't have that problem at all when you look at the graphs.
LINK
I really regret that I bought my G27 and wish I would have known that before it was too late.
If you have the money, go for a better wheel! If you don't have the money, look for a used G27 and you won't waste that much money for a "not so good" wheel.
If it's really a decision between these two: I would take the G29 because you have metal-pedals (but no angle setting, which I don't miss) and leather and overall it feels nicer! I read more positive reviews about the G29 than about the T150!
That all said: you can be fast with all of them! The question is for you, how important a really good and nice feeling is