ASUS A45VS-VX026H, i5-3210M + Nvidia GT645M@RM2199[2.4kg], 2GB, 500GB, W8
Dell New Inspiron 14R, i5-3337U + Nvidia GT730M + (1366x768;touch)@RM2099[2.33kg], 4GB, 750GB(5400rpm), Linux; W8@RM2399
HP [Ultrabook] Envy4-1204TX, i5-3337U + AMD HD8750M + 32GB mSATA +500GB(5400rpm)@RM2399[Beats][1.75kg], 2GB, W8
Lenovo Z400 touch, i5-3230M + Nvidia GT740M + (1366x768, touch)@RM2399, 4GB, 1TB, W8; 2 years warranty
Lenovo Ideapad Z580, i5-3210M + Nvidia GT640M@RM2299, 4GB, 750GB(5400rpm), W7HB, white

price is RSP and negotiable. best selected for you is Lenovo Z400 touch, 2nd is Dell New Inspiron 14R with touch and 3rd is Lenovo Z580.

im not sure about acer though but for ASUS, their warranty support is haiz. actually, the lenovo Z400 is pretty slim. they are ultrabook like laptops with consumer line specifications. but the battery performance will be bad compared to other ultrabooks, as it is not an ULV processor.

You can also consider:
Lenovo New Z400, i5-3230M + Nvidia GT740M@RM2099, 4GB, 1TB, W8; 2 years warranty; colors: chocolate

Here the review from Z400 user~raeimad:
"this laptop has around 4 hours or normal usage (intel HD4000) usage and around 3 hours when I played Need For Speed Most Wanted 2012 on full graphics"

Acer V5 battery life also not very good since its using lower capacity battery:37 Wh 2500 mAh 4-cell Li-ion battery pack. More details review here: http://www.notebookcheck.net/Review-Acer-A...ok.87600.0.html
Comment by noteboocheck reviews: short battery life, because of a small battery.

Performance: Z400/GT740m > Envy4/HD8750M > V5/GT710m
Warranty support is around the same standard.
Best price/performance: Z400/GT740m@2099.

Since you are casual gamer, perhaps Z400 is the best choice. 

All can upgrade ram, ssd. Suggest to ask the reseller to upgrade the ram & ssd for Z400 if needed, it will save the hassle for you.

It all depends on whether you prefer lightness (14" Envy4 ) or productivity (15.6" Z500) 

Yup 

If you prefer a light notebook, then the U940 is definitely the better pick here
15 inchers are pretty bulky to bring about, even when some of them are quite slim

Lenovo Z series has much more powerful CPU & GPU compare with Toshiba U ultrabook
But if you are not inot gaming, get laptop with full SSD (128G) or upgrade aftermarket. It boost responsiveness tremendously

Dell
Vostro 5460, i5-3337U + Nvidia GT630M + (32GB mSATA SSD + 500GB(5400rpm))@RM2199[1.54kg], 4GB, W8SL, 3 cell

HP
Envy4-1204TX, i5-3337U + AMD HD8750M + 32GB mSATA +500GB(5400rpm)@RM2399[Beats][1.75kg], 2GB, W8
Envy4-1238TX, i5-3337U + AMD HD8750M@RM2099[Beats][1.75kg], 2GB, 500GB(5400rpm), W8

Lenovo
Z400, i5-3230M + Nvidia GT740M@RM2099, 4GB, 1TB, W8; 2 years warranty

Envy 4 line up has been quite a while, HP update the specs from time to time.
If you go for HP, I suggest you take the 1238TX, then swap out the HDD for a SSD (128G ~ RM300+/-). Give you much better user experience vs the 1204TX stock spec.

Z400 is quite new. But it is not an ultrabook, even it is thin. The i5 M CPU plus the small battery won't give you good battery performance.

If you go for the Dell, extend warranty to 3 years on site (~ RM250).

If you intend to game on any of these models, make sure you get good external cooling solution (eg. cooling pad, table fan ...).

Prices are RSP, negotiable.