If you have the time, don't plant diamondates, plant upgrapes or rushrooms.
Per Farm math:
Upgrapes are 8,000/planting and the yield is 100.
Diamondates are 75,000 and the yield is 800. If you divide that by hourly, you spend 15,000 and get 160.
If you plant upgrapes twice, you get 200 for 16,000. You can plant 6 times and get 600 per hour.
If you don't have that much time, but more time than having to leave the game for 5 hours, plant rushrooms.
Rushrooms cost 26,000 and yield 300.
If you plant them 3 times, you spend 78,000 and the yield is 900. That's 3 hours of planting, you can plant 5 times and get 1500 if you have the money.
Now that I have a lot of coin, I plant upgrades, rushrooms and diamondates almost exclusively. Sometimes I plant buffbeets or impruberries for bingo but almost never fireapples or pumpwings (fireapples when Tales calls for it), Eliteleeks only during World event since hours of farming matter, and NEVER Scalypears.
I plant upgrapes most often, rushrooms when I'm busy at work, and diamondates overnight (except World Event).
When I use the boosts, I almost always plant rushrooms or upgrapes. With the 5X boost, upgrapes take 2 minutes to grow and about 20 sec to harvest/replant so I get 5 in about the same time as rushrooms, about 25 upgrapes (5 rushrooms) in the same time as diamondates
With the 10X boost, I usually plant rushrooms. They take 6 minutes with about 20 sec to harvest/replant. I get about 4 of them in the same time as diamondates. I have planted upgrapes before and the yield is still the best but the game tends to crash during the hour, which is frustrating and also I really have to pay attention to the game since I'm harvesting/replanting every minute.
Also, if you have gold and need food (or harvesting time for points for World Event), use the 10X boost, plant diamondates and you can harvest right away for one gold instead of 5 since the crop will be ready within the half hour.