This is a great "Mad Libs" type question, but the answer would be the same even if you were asking "Are Elephants likely to have more sex partners than Ghosts?"
Simply put, number of sex partners is determined by the following:
- Demand for sex
- Supply of compatible partners
While demand for sex can, at times, seem pretty universal, it isn't always so. There are people who don't appreciate sex, or who are intentionally abstaining for a variety of reasons.
Supply, on the other hand, is affected greatly by location and social contexts. Thus, it's impossible to universally generalize about gay men and lesbians in this way, without providing some additional context and/or a locale.
If you asked something like "Between male and female homosexual residents of San Francisco, which is more likely to have (or have had in the past) more sex partners?", we could start to draw on social data sources, anecdotal experiences, subcultural preferences, and general social tolerances specific to the bay area/SF itself that could help make such a determination. And those results might vary widely from similar groups in Austin, Miami, Chicago or Vancouver.
Simply put, it's impossible to judge based on the question as worded.