I had auditioned both the TVs and more than once actually, but not side-by-side. Like you, I also found SL90s picture quality to be very good. I had compared SL90 side-by-side with Samsungs B6000 and thought SL90 was marginally better in terms of PQ. Before that, I had done a similar side-by-side comparison of LH90 & B6000 and concluded that LH90 had noticeably better PQ.
I booked 47SL90, but couldnt get it for weeks after the booking as stocks for the 47 model was taking ages to arrive. I ended up buying 42LH90.
Reason: I was trying to find a 47 model within my budget, but at the same time didnt want to compromise on PQ. I was convinced in terms of PQ LH90 was better than SL90. But when I started looking around, LH90 47 model was discontinued and even 42 one was also very difficult to get. Then in early Jan SL90 was launched. I liked it I thought though its PQ was probably not as superlative as LH90, it was still very very good and in fact as good or better than Samsungs B6000. Besides, I surely liked its stunning looks. So I booked 47SL90. After about 3-4 weeks of painful wait, I was told it would take some more time to get the 47SL90. The same dealer also informed me that he had just got new stock of 42LH90. Not willing to wait any further, I had fallen back on 42 models and settled for 42LH90.
You cant go wrong with LH90 in terms of the PQ, especially because of the local dimming technology that it has I believe no other LED-backlit TV available in India has this.
So purely in terms of PQ, I would recommend LH90 ahead of SL90. Also SL90 has a glassy front panel, which is a bit reflective this will matter only if you watch TV in a brightly-lit room.
But if along with PQ, the look and size of the TV is also an important consideration for you go for SL90. I had measured and found that 42LH90 has almost similar (overall) width as the 47SL90! And LH90 surely is not sleek.
