There are 2 issues: award levels and award availability. Things have changed a lot on this route. Redemption levels are all over the map. BA used to have one of the best levels for J/F and has now gone to one of the worst. AA decreased J from 150,000 to 135,000 but eliminated the pacific routing (on CX or AA/JL). Star carriers have different levels and some of the levels have been posted earlier in this thread. The Mexicana/Star route was a great option (I learnt about it on FT) and is soon unavailable.
In addition to the redemption levels, the challenge on this route is award availability. India is tough place to get award travel at peak times. You are fine during non-peak travel. Peak travel time has been increasing in duration. It is now Dec-Feb and again June-Sep. The peaks are driven by huge numbers of overseas Indian heading to meet families and by tourist arrivals in the colder season.
I have preferred OW to Star in the past for my travel. Star frequency was always better but OW had good RTW fares from India. Now Star may become a better choice because of the limited open-skies initiative by the Indian govt which allows TG/SQ to increase capacity. With AC adding new service, LH increasing capacity availability on Star is definitely increasing.
My understanding of some of the "politics" on this route and why that affects FF award availablity. India has limited open skies with select countries and used to demand parity in bilateral agreements. This means that routes via LHR are constrained by BAs refusal to open up slots for Indian carriers (though AI is one of the few airlines to enjoy special rights on LHR-North America markets). This leaves BA from getting better access to the Indian market. LH signed a decent deal and is able to increase a lot of frequency to India (in addition to DEL/BOM they also have BLR-MAA; this is great if you need to bypass DEL during fod). SQ has a lot of frequency and is now expected to add CCU in addition to a lot of interior destinations. TG has added MAA and is adding BLR and other Budhist tourist destinations. In all Star carriers are going to be increasing capacity massively to India compared to OW (LX- Swiss will join OW in early 2004 and increase OW capacity a little but they have already dropped the ZRH-DEL route and only fly to BOM for now).
Outside of the Star network, DL, AF, NW, CO, KLM are not too bad. Redemption levels are decent and non-peak availability is good (except CO). I am not a fan of their BF product and the general lack of 3 class service.
EK flies to a lot of destinations in India and does not have flts to NorthAm for now. It is planning to add US services in 2004 and they do have plans for a fantastic J/F product. EK or their partners (I do not have redmeption experiences with them) may be a good options. They offer double miles for online booking but you may get better prices through ethnic agents.