Gel results are definitely something to consider, but I prefer to choose rounds that have a good track record in actual shootings, too.

My first choice is the Speer 135gr SB-GDHP (all 135gr Gold Dots are the short-barrel version) and my second choice is the FBI load, with BB standard pressure being my preferred version.

There may be more modern loads available than the FBI load, and it may not perform ideally in gel, but I don't think one should ignore the long track record this type of load has made in LE.

If I couldn't find those loads, I would go with whatever modern, medium-to-heavy-weight HP with a good reputation for reliability I could find.

As far as +P versus standard pressure, I do think that +P can be worth it in .38 snubs. The caveats are that 1) the gun can handle it, and 2) the shooter can handle it. FWIW, even though BB says their FBI load is standard pressure, I treat it as +P because of the velocities it generates.