User blog comment:Arkxiah/These summons recently/@comment-1036329-20170615025145

Resummon gates are a pretty good deal, you get up to four summons for the price of two, having the option to replace one or both of the first two summons if you don't like them. But read up on the units that are on rate up first to see if it's worth it for you to summon for them. If you're not interested you're better off waiting for a different gate.

There are also Omni-only gates, gates like Spring Summon that give you free tickets, event dungeons that drop Omni/capable units, Login Bonus and Milestone Reward Omnis, and Super/Honor Summon for the starters, which won't cost you a single gem. The free units aren't that great but are viable enough to tide you over until you manage to roll a meta unit.

If you're only looking for omnis I'd stay off  5* and up gates unless they're on discount and hold your gems for a Limited Edition you like or a gate with a meta unit, so you have a chance for the unit on rate up and a chance to get omnis from noise pulls.

Getting 5-stars aren't a complete loss, though, You'll be needing some for SArc.