The Passuk commanding Bikkurim (Exodus 23:19) commands the “choicest” fruits.
Were any bikkurim offerings (from the last prescribed species) ineligible for offering because of being too ripe, not ripe enough, too small etc.?
The Torah prohibits blemished animals for certain Korbanot, but are there any issues with the quality of certain fruit offerings?
Indeed fruits of inferior quality or rotten were not acceptable. The Rambam writes (MT Bikkurim 2:3)
We do not bring [first fruits] from the dates in the mountains, nor from the fruit from the valleys, not from oil-producing olives that are not of the highest quality, but rather from dates from the valleys and fruit from the mountains, for they are of the highest quality. If a person brought first fruits of inferior quality, e.g., dates from the mountains, figs that were perforated and had oil applied to them, dusty and smoked grapes, they are not consecrated.
and 2:20
When a person set aside his first fruits and they rotted away [...] he is obligated to set aside others in place of them.
Note however that bikkurim were not offerings in the sense of being offered on the altar, instead they were to be brought to Jerusalem in a procession, presented to the priests and eaten there (details here).
