.
Postpaid GX68 is unlimited speed but video-streaming is limited to 1080p/FHD/3.5Mbps. GX50 has speed cap of 5Mbps and same video-streaming limit.

Eg GX68 is much quicker when downloading a large file of >10GB in size. 4G's normal download speed is about 30Mbps = takes about 1hr to d/l the 10GB file. If 4G+(= normal speed of about 120Mbps), even faster.

https://www.u.com.my/plans/postpaid/gilerunlimited
.

.
This is what a person should know and do before subscribing to a celco plan; .......

From the opensignal website, overall best celcos are the Big 3 pioneers, ie Maxis, Celcom and Digi. For best rural coverage, it is Celcom, a GLC. The smaller newcomers have good coverage and service in mostly urban areas, ie UMobile, YES and TM Unifi Mobile. Yoodo, XOX and Tunetalk are MVNOs which lease lines/bandwidth from the Big 3 celcos.

1) Research for the best and suitable offer from celco, eg prepaid or postpaid, data quota or unlimited data, limited speed or unlimited speed, limited or unlimited local calls, do you travel/move around alot?, etc.

1.1) Check the 4G LTE frequency Band support for both your phone and your chosen celco, eg most mid-end to high-end Android 8.0 or later phones support all the LTE Bands, U Mobile supports only LTE Band 7/2600MHz, Band 3/1800MHz and Band 1/2100MHz, TM Unifi Mobile supports only LTE Band 5/850MHz, Band 38 and Band 40, etc. Other celcos may use different 4G-LTE Bands, eg Band 8 by Maxis. Low-end Android 8.0 or later phones may not support a few 4G LTE Bands.

2) Check the 4G/3G coverage map for your chosen celco at their websites or at nperf.com.

3) Best to buy a RM10 disposable prepaid Starter Park to do actual speedtest at your various frequented locations for a few days.
Eg got 1 TM Unifi Mobile postpaid unlimited-data RM59 promo with 1-year-contract subscriber did not do this test in April 2020 and later found out his house location could not receive 4G Internet data but could only make 3G calls/SMS. TM diagnosed his problem to be a large highrise building near his house blocking the 4G cell signals.
....... Got another subscriber was given a free mandatory cheaper (than Maxis) postpaid U Mobile P70 plan by his employer/company but his house has no to little 4G coverage but could still make 3G calls/sms.

Note that a 4G/3G cell tower has a range of up to 3 miles/5km for Internet data and up to 20 miles for voice calls/SMS. Today, most Internet data runs on 4G while most voice calls/SMS still run on 3G/2G. Ensure you have 4G network coverage for Internet data from your preferred celco.
.

If you are using a oppo / realme / vivo phone, make sure that the phone has 4G band 7 in order to use U Mobile.

Go to buy a U Mobile prepaid and try to use all the apps in all of your locations first, if the line is good in all locations, then you just go to subscribe the GX68 plan.

thinking to switch from digi to umobile since their cheapest plan also offer 5g.

anyone can share experience for umobile 5g around kl sentral / bukit jalil area?