Pretty much all 48" T8s are energy saver bulbs. The "old" discontinued standard 48" T8s were 40 watts.
Tommy
Not quite. As far as "standard" 4' lamps go, T12 are 40 watts, T8 are 32 watts, and T5 are 28 watts. Energy saver T12s are usually 34 watts, T8s are usually 28 or 25 watts, and I'm not quite sure if energy saver T5s are a thing.
Unless you opt for a high lumen lamp, pretty much all lamps of a similar category (size, color, and power consumption) will be within about 100 lumens of each other, especially for T8s. Energy saver lamps will sacrifice light output and cold weather performance, so the average person here probably isn't interested in them. And unless you are willing to order high lumen lamps from a supplier, you're mostly confined to what Lowes/Home Depot sell off the shelf.
This means you're pretty much choosing based off of color. Color temperatures of 3000K, 3500K, 4100K, 5000K, and 6500K are the common choices. Higher color temperatures are cooler looking light. 3000K is pretty warm and incan like, but if you're priority is matching incandescent light you'll have to hunt down some 2700K lamps. 3500K is a nice happy medium between warm white (3000K) and cool white (4100K), and is my personal choice for lighting a more relaxed space. Next you have 4100K, which is also called cool white. This is probably the most common color, and has been lighting offices for the past 50-60 years. This tends to be the only color you can get at Home Depot in a 30 pack. After that, you have 5000K. This is the color of direct sunlight around noon, and is my favorite for lighting workspaces. It looks good at high light levels, and is good for keeping you alert. Finally, you have 6500K, which is the color of indirect daylight. This is also a good color for workspaces, but some people find it too blue.
I'll briefly touch on CRI (color rendering index) here, as well. T8 lamps are available in two common grades, ~75 CRI and ~85 CRI. Most lamps at a big box store will be the higher grade, the only color the lower grade is common in is cool white (4100K). If you can't find the CRI on the box, you can tell by looking at the lamp code. The first part of the code will look like F32T8/741 or F32T8/SPX50. The F32 tells you that the lamp is 32 watts, but energy saver tubes have the "normal" tube wattage there, not the actual wattage. The next number (T8) tells you the diameter of the lamp in eighths of an inch. The part after that is the color temperature and color quality. The hundreds digit, or letters tell you the CRI (7 or SP= ~75, 8 or SPX= ~85 CRI), and the last two numbers tell you the color temperature. 30=3000K and so on.
This ended up being pretty long, but I hope someone finds it helpful.
If you need more than a few bulbs you can save a lot of money by ordering online from a place like 1000bulbs.com, even after shipping. They have a lot more choices for colors and lumens too.