Technically you could replace them with just about anything. It's a standard socket. Otherwise you just need the "type" on the base like the other post stated to get the same shape. Matching the exact light color may prove difficult though if you care about that. You can try to find 2700k fluorescent g25 bulbs to get the closest match. An led will probably look a bit different for color than your current fluorescent bulbs even with the same color rating.
If you want to start swapping them out or just replace them all then led often lasts longer and uses less electricity so switching could be a good idea. The k number on the bulb is the color of the light. 2700k is very soft white (yellowish), at about 6,000k the light takes on a bluish tint and seems dimmer again, and in the middle is variations on whiter, brighter seeming light than the 2700k. I hate that dingy yellow so I'd probably just swap them all out for some cool white (~3,500k) led version of the g25 shape but it's a matter of preference.