Garrett Block :
Should i get a different card?
what is your exact budget?
270X is definitely better. no contest. but it also consume a whole lot more power than 750Ti.
you can take which ever you want but performance wise which is what really matter in gaming leans towards 270X
Garrett Block :
Does nvidia support more games?
both company were about equal in this matter.
Garrett Block :
Is amd mantle worth it rather than nvidia?
problem is not all games will have mantle due to it's nature. for AMD user that is something extra for them.
Garrett Block :
which has better customer support?
maybe nvidia. i haven't use radeon for a very long time. this is something for people that use both brand at the same time
Garrett Block :
Which is more reliable in terms of driver updates??
nvidia seems releasing more drivers than AMD right now. it the past it was the opposite with AMD promised to release new drivers each months. in the end they stop that because it doesn't really help them but instead create unnecessary burden on their driver team. also AMD drops driver support much faster than nvidia. the recent example will be the upcoming DX12 support. while nvidia will support DX12 down to their 400 series card (that's mean all their DX11 card) amd will only supporting DX12 with GCN based card. their 5k and 6k (which also DX11 based card) will not going to get DX12 support. i asked about this myself to Robert with Tom's Hardware AMA (ask me anything) with AMD earlier this month.
Garrett Block :
How long will either card last?
both sits on different performance tier. but for this question it depends on how you like to play your game. i mean at what setting you willing to play.
Garrett Block :
Does it work well with the components im using?
you only mention about CPU and RAM. what is the other component? especially PSU