The best replacement for mvc 3 is mvc2.

The best alternatives to mvc 3 are rated as following:
★★★★★  mvc2
★★★★  mvc 2
★★  jsf 2
★★  mvc 4
★★  web forms
★  webforms
★  rails 3

Your alternative for mvc 3 is not listed? Suggest!
Speaking about mvc 3, one probably shouldn't forget about web api.

Other search terms related to mvc 3 and their ratings are:
★★★★★ web api
★★★★ iis 6
You have in mind a companion for mvc 3 and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of mvc 3 in all years. Click on graph for more.
mvc 3
mvc2
mvc 2