It depends....
If you can't take advantage of the Annual Pass, there really isn't much savings with the non-expiring ticket unless
(1) you're taking advantage of the Park Hopping and/or Plus Options OR
(2) you're doing short park trips (less than 4 days with each trip)
NOTE: Ticket prices go up every year. So the more days you buy in advance the more you'll save in the long run. But the overall savings may be very little depending on the ticket purchased.
For example
If you decided that you wanted the MYW base ticket only (one theme park per day, no park hopping, no plus options, expires 14 days after 1st use) then
A 10day MYW Base w/no expiration ($481.38) is almost the same price as buying a 5day MYW Base Tickets expiring ($242.82) for your 1st visit + a 5day MYW Base Tickets expiring ($242.82) for your 2nd visit {$242.82 + $242.82 = $485.64}
A 10day MYW Base w/no expiration ($481.38) is almost the same price as buying a 7day MYW Base Tickets expiring ($249.21) for your 1st visit + a 3day MYW Base Tickets expiring ($233.24) for your 2nd visit {$249.21 + $233.24 = $482.45}
If you're normally in the park only for 1, 2 or 3 days max during your trips then
A 10day MYW Base w/no expiration ($481.38) is a better deal than buying several 3 day MYW Base Tickets expiring ($233.24) for each visit {$233.24 + $233.24 + $233.24 = $699.72}