For BI - obviously EB + bi.exe

For M2TW - surely the EB2 - pity it is still in development

Spoiler Alert, click show to read: 
Seriously, I am unable to say much on M2TW mods, as I do not have M2TW yet (waiting for EB2), but I have heard that Stainless Steel and Broken Crescent are both very good.

As for BI - RTW TIC is pretty good, even if rather narrow focused and therefore featuring rather short campaign. Definitelly worth trying. Outside the EB timeframe I am tempted by Invasio Barbarorum - Flegellum Dei, even if I have not played it yet myself.