While I like the addition of Oaks sometimes (albeit rarely) dropping apples, I still would rather see real apple trees in Minecrafts. I don't think that's going to happen, so I'd like to see a mod for it, but not one that adds a bunch of trees, like premium wood. I think apple trees should either come from apple seeds (craftable from apples) or apple tree saplings, which would be an even rarer oak tree drop. Apple trees are essentially oak trees, but with different leaves (both in texture and apple drop rate). Apple trees sometimes spawn in the world, but they're not too common and on addition to deserts and plains, they won't naturally spawn in Taiga and Tundra biomes.
But wait, there's more. Seeing how someone brought up the idea of golden apple trees in Suggestions (which is where this idea came from btw), I'd like to see Golden Apple trees in this mod as well. Golden Apples and Golden Apple Tree saplings would be extremely rare drop (Golden Apples themselves are even rarer than the 1 in 200 drop rate of Apples from Oak Trees, the Saplings would probably be 1 in 1,000) from Apple Trees and never drop from Oak leaves. Oh, and speaking of saplings rarely dropping, Apple Tree Saplings are still fairly rare in even Apple Trees. Golden Apple Trees have a 1 in 50 chance of dropping Golden Apples and a 1 in 250 of dropping Golden Apple Tree Saplings. They also have a 1 in 750 chance of dropping a Diamond Apple.
Diamond Apples? Crafted from 4 diamond blocks and a golden apple, Diamond Apples would be the new superfood of Minecraft. Diamond Apples not only give you 45 seconds of Regen II and heal 7.5 hunger bars, but they also make you Fire Resistant for 30 seconds. Diamond Apples can also be obtained from random loot chests in Strongholds. (If it has to be, set it up to only come Library loot chests, to make sure you only get them in Strongholds.) Even so, the chance of finding one in a loot chest is four times rarer as the rarest thing.
Speaking of crafting, in this mod, the Golden Apple recipe could be changed to ingots and the Regen would be brought back up to 10-15 seconds (maybe 12), in order to make them worth getting again. This would make the trees worth having and make killing Mo Creatures Werewolves (while having this mod) worth killing again.
Anyhow.. here's a better rundown of the chances.
1 in 200 Apples
1 in 500 Apple Tree Sapling
1 in 25 Apples
1 in 250 Apple Tree Sapling
1 in 200 Golden Apples
1 in 1,000 Golden Apple Tree Sapling
Golden Apple Tree
1 in 75 Golden Apples
1 in 750 Golden Apple Tree Sapling
1 in 1,000 Diamond Apples
1 in 2,500 (or at least four times rarer than the rarest stronghold loot chest item)
Crafting them of course wouldn't be super hard, but think about. With 36 diamonds, you can..
Craft a full set of armor
Make an Enchantment Table
Make a nearly full set of tools
Unlike the Golden Apples, the material you're using is actually useful, beyond power rails and making several glisterning melons. Would you really use your first 36 hard-earned diamonds for one Diamond Apple?
Edit: I forgot to mention, but part of the idea was also to specify that Golden Apple Trees have a set of condition that need to be fulfilled before they can grow, including.. no sand or gravel within 5-10 blocks of the growing space and to have lava and water within 5-10 blocks of the growing space. Also, Golden Apple Trees would have their own texture for both leaves and wood. (imagine at least a golden Oak wood texture)
"I don't plan to add a new dimension at the moment. It's just to performance heavy on servers, and the current dimensions need more attention before we start adding new ones." Yeah, like biomes or actual varied terrain in the nether. Nether ruins didn't do the trick at all.