In this corner Groove Glide...

and the challenger is Last's record preservative. I have not tried gg, but there seems to be some discussion of a post cleaning step yea or nea. I use Last on all used records and nothing on new ones. Thus far happy with reduced noise and no back of the hall reduction in intimacy from those just cleaned but nothing extra. But I could be wrong. What say ye?
Never tried Last, but I like Groove GLide.
I have both products. I like Last Preservative and do not like Groove Glide.

Last reduces noise with little or no change in overall tonal balance, dynamics and bandwidth. More importantly it drastically reduces record wear for dozens of plays.

If an attribute had to be assigned to magnify the sonic differences between Last and Groove Glide, Last is VERY slightly brighter sounding (you must really listen to pick up on this) while Groove Glide lessens immediacy and impact of all frequencies, but particularly the high frequencies.

It's likely people will disagree on which is better depending on their cartridge and overall system balance. A friend that owns a "hot" Clear Audio cartridge prefers Groove Glide but when we listened to an LP treated identically but using my Koetsu Rosewood Signature Platinum, The Last was clearly superior.

I might add here, I never treat with Last and then immediately play the LP. I always do an additional rinse using Record Research and my VPI record cleaning machine.

Once Last has done it's job (the first few seconds after applying), it has done all it will do. However, I believe it leaves behind some audible impurities as the RR fluid is a must on my system. With this final rinse, I wind up with all the advantages of Last and no disadvantage that I can detect.

You may also do a final wash with RR fluid after applying Groove Glide, but the Record Research will remove it completely, putting you back to an original untreated LP.

I have LP's that were treated with Last in the 1970's and still play as new. Even if the performance of these two products was identical after treatment and first audition, I would still choose Last because It has proven itself over time.
I agree completely with Albert. On Lp's on which I apply LAST, I follow the same procedure as LAbert using RRL fluid. LAST is meant to be a record preservative, as in preserving the vinyl. I think, and correct me if I am wrong, but GruvGlide is not intended to protect the vinyl perse but, rather, acts as a lubricant and in reducing static (better solved with a Zerostat, IMHO). I recall the LAST making a claim that it molecularly binds to the vinyl where as the GruvGlide does not.
I've used both and the Last is a great product. My turntable uses a felt mat and the static from it is problematic though. The record generally lifts the mat on removal from the platter. Then I need to peel the mat off the record and put it back on the platter. The Gruv Glide solves this problem. I've found that the absolute barest application provides all the benefits and I don't hear any degradation in my system. I also don't experience the gunk build up on the stylus that is often referred to. Of course, it's modest by Audiogon standards and I'd be foolish to think it would pick up the subtle nuances of a system like Alberts. I have tried two other mats previously that degraded the sound IMO. Simply put, the music lost whatever it is that makes my toe tap or my foot keep time with the music. I've own a Zero Stat and used it religiously until I discovered Gruv Glide. It saves a lot of time (especially when I have a listening partner) and I experience no ill effects from its use. YMMV and all that. A little science never hurts.
Years ago (15-20) I used LAST on my records and still play them with no ill effect.

I was just looking at one of my LAST stickers last night (the little dot on the record lable after you apply LAST) and wondering if there would be an improvement in sound if I had not treated it after all these years, as I was young and inexperienced in the ways of HI FI when I did use it, the posts above have made me feel better about that.
There was a time when I put Last on most of my records. There was a time when Lloyd Walker convinced me to use Gruv Glide. I used it on only about 10 records always after a thorough cleaning. After a one time listening, I hated the Gruv Glide thereafter. I then spent a good deal of time repeatedly cleaning my records to remove all traces of the Gruv Glide. I now understand that there is a Gruv Glide II which supposedly leaves less residue. I will never try it.

I have lately found that my Last treated records also benefit from a thorough cleaning on my Loricraft. I much prefer the sound having removed the residue of the Last.

In short, I think both products hurt my LP performance.
Thanks for all your information. I too have the static electricity lifting my mat with record. I need to experiment with a post-last rinse.