On their first year (everbearers) I remove all of the spring blooms and runners to allow the plants to make good roots, then for the late crop they will bear steadily over a period of several weeks, mid-August up until first frost. The fall crop is always the best because they will stop bearing during the worst heat of summer and just work on growing. Your second year with them will be even better and they should do well for you up until 4 or 5 years of age, which is then time to replace them because they'll start to die out. If your plants are disease free, you can keep your patch going with your own runners, or buy new plants...either way. (Don't let them make too many runners per plant though...it will sap their energy. I only leave 3 or 4 per plant, just to have replacements. You can keep pruning them all off if you want to.)
Everbearers are nice if you want a steady supply of berries for a few pies and handfuls of berries to throw in your breakfast. They don't lay on huge crops like the Junebearers do, which is probably where you're seeing the difference after raising Junebearers. The Junebearers are best for folks who like to make a lot of jam and put up lots of berries for winter. You get heavy crops over a couple weeks and can process them all at once. Everbearers are slow and steady.