Both are the good books but I would suggest you first to go for NCERT books as it will help you to build your concept. Other books also you can prefer:

Physical Chemistry by O.P. Tandon

Modern’s ABC of Chemistry for class 11th and 12th

Dinesh Chemistry

For NEET Chemistry preparation you should complete your NCERT book first. So, that your basics are clear and you build strong fundamentals.

After, completing NCERT you can go for other recommended books. Both the books MTG and Arihant are good for preparation but if you have to choose one you can go for Arihant.

All the Best!!