IMHO, comparing silicone vs. acrylic latex is like comparing 10, 20, 35, and 50 year caulks. They all keep out the water, but is their really that much of a difference? Probably but not necessarily enough to matter. A 50 year caulk will outlast your tub and it will discolor before then anyway. Tub and tile caulk is supposed to help avoid mildew, etc.
Silicone is more flexible but is much harder to put on. It is much harder to dip your finger in water(or dish soap as some do) and get a nice looking bead cause it is so sticky. Once it gets on the wall or tub where you don't want it, it is hard to wipe off. Acrylic latex wipes up easier with your finger and wipes off the wall with a rag. Pure silicone is ok for the pros who caulk all the time and have mastered the technique.
The DIYer who hasn't caulked much is better off with acrylic latex cause it is easier to make look good. Compromise like some and use a 35 year acrylic latex "with silicone". Use the color that goes on white and dries clear.
Use a good brand and buy extra and go out and caulk your windows and doors first. They probably need the caulk and you can use the practice before you tackle the tub. Clean the buildup off of your finger and rewet it regularly. Don't lay it on too thick. It is not like glazing a window. Good luck.