IIT

That will be based on the cutoff,competition etc. You must wait till the results

NATA exam and scores are compulsory for taking admission into any architectural college in India, EXCEPT IIT's and NIT.
NIT- Takes admission in architecture on basis of JEE Main Paper 2
IIT's-Takes admission in architecture on basis of Architectural Aptitude test
So you can prepare accordingly

step 1 jee main
step 2 jee advance

when compared to least ranking IIT's .top ranking NIT's are the best

Obviously,because every IIT has a world rank,the syllabus accepted by the Brand MNC'S so It is really "best" choice to do it from iit.

Hello ! since you have not done well in JEE mains , dont worry there are still many colleges who conducts their own entrance examination.These colleges are doing equally good as top Government institutions,so why to waste your precious one year when you are having a good colleges to get admission.here are some of the colleges where you can get admission:
1.Lovely Professional University
2.BITS
3.Symbiosis
i have heard that Lovely Professional University provides scholarship upto 1.5 lakh per annum based on your score in their Entrance exam.even these universities provides assured placement.