Manga Kissa, or Love Hotel for Osaka?

My friends and I will be traveling this winter break through Japan and have booked all of our hotel stays in advance already, except for Osaka.

We were interested in just playing it by ear/eyes and experience sleeping in either a Manga Kissa, or a Love Hotel.

My question is, which would be a better option? we're not looking for anything fancy, we just wanted to try something new, a friend mentioned to us that he spent the night at a Manga kissa for $10, and for $3 he could've gotten a shower too.

Do you know of any good Manga Kissas or Love Hotels near Osaka Station?

And 1 last question, where is there a place to hold our luggage while we are around traveling during the day (in Osaka) if we don't have a hotel to leave it in? We're traveling pretty light, but would still like to leave our stuff locked up somewhere safe.

I can't help you with your main enquirey but I can help on baggage. At Osaka JR (Umeda subway.... it's all kind of the same building) there are large coin lockers. I have even put a big backpack (not day pack, like a backpacking pack) in one with no worries. They're not too expensive and they are secure. A word of warning: Do not cram more in the locker than it is designed to hold, it can cause them to not re open... it happened to me when I used a smaller locker. Lesson learned.

While Manga Kissa only have separate booth with soft flat floor or reclining chair,
you can sleep on a bed at Love Hotel and far more comfortable.

But there is a possibility that a Love hotel not accepting more than 3 ppl in one room,
for they fear sexual abuse or criminal action to be carried out in the hotel room.

Another problem you need to keep in mind is that
Manga Kissa usually requires membership registration
and some are very reluctant to accept foreign guests.
We Japanese are usually very weak to foreign language,
and some even fears those whom we cannot communicate in Japanese.

However, Manga Kissa in large city such as Tokyo or Osaka would be used to accepting
foreign guests with visitor price system so don't worry too much.