There is no Fannie Mae or Freddie Mac with HELOCs, so each lender makes up whatever terms/guidelines/rates/etc that they want.
Hardcore rate/term shopping lenders for a 1st position mortgage isn't going to make a huge amount of difference (relative to also comparing reliability, knowledge, etc), but for HELOCs it will because the rates/terms vary so much in the HELOC world.
Often, but not always, regional banks or credit unions will be the winners.
Prime rate is 3.5% that is the benchmark for an A paper borrower. If there is an intro rate, make sure you know what the rate is after it expires. Are there closing costs admin fees, prepayment penaties?
Start at Bankrate make at least half a dozen calls including your current bank and try to find the best Credit Union solution as I agree with what Chris M mentioned. TD Bank and Third Federal look attractive but I don't have your scenario info to know what you qualify for.