I've SBIMTGS '93 scheme and Birla equity plan also but almost 40% times I felt that they were laggards among ELSS MFs but this year I invested in DSPML Tax saver just to save entry load coz I had to switch from DSPML Tech.Com MF coz of $ depriciation but it turned out better than previous ELSSs. Now I will invest all 80C limit in this ELSS. I've RIL, LNT, NTPC, BHEL, POWERGRID etc. Total 13 large caps. So I am free to invest in small n mid caps and you have to be well diversified and long term specially for small n midcaps. So what could be better than such an ELSS. Principal tax saver @ Principal personal tax saver are in my watchlist.
One thing more as age increase one should shift towards large cap ELSS like HDFC tax saver.
As far as SBI MF schemes are concerned they are no more in toppers since when Sabharwal left SBI in dec 2006 and joined JM Mutual Funds (JM BASIC).