On the Vacuflush system that I used to have where the tank was separate from the pump I used Quilted Northern two ply for six years with no problems. On my current boat which has a Vacuflush vacuum generator (pump mounted on tank) I use Thetford or Coleman from Walmart. The vacuum generator is not as strong as the set up where the tank and pump are separate. The Sealand TP from West is too thin, if you know what I mean, and is too expensive.
If all else fails but the cheapest and thinest that your grocery store has.
BTW, about a year ago I held the great TP disolve off in Baltimore on July 4th. All forum members were invited. Only one came. The winner in quick disolve was Quilted Northern Two Ply. Why two ply? I don't know. but it is quick to disappear.