I would say go with shrooms first, but try both...lol Both can be very visual and fun, full of laughter, fun times and great memories but it all depends on the quality of what you are taking. I've taken very little amounts of shrooms, (like a half 1/
and tripped fairly well with good visuals and taken larger amounts at times and felt less. My very first time I shroomed in college, I took 1/4 of some liberty caps and was goin strong for 16 hours... very unbelievable visuals, cartoon like effects to the world, but no bad experienced...
Acid is fun, however, it can be a bit intense at times because it seems to grasp hold of reality vs your percieved reality and makes you kind of unsure at times what is real. Acid has some fucking awesome visuals if you take good amounts of pure shiz but even someone who has done it a number of times can get overwhelmed and freak out if a bad situation were to arise. I would recommend getting gel tabs if you are going to do acid...very fun, 1 should be enough for your first trip, but have an extra cause 4 hours into it you may want to take it...lol...Have a good friend with you when your doing acid, someone who you are very comfortable with, cause if you have a bad moment, it helps calm ya down..
Acid is definitly more of a mind fuck where shrooms you are a little more grounded....think of acid like an intense dream you see, where as shrooms your watching cartoons...