When comparing Atlas vs QKSMS, the Slant community recommends QKSMS for most people. In the question“What are the best Material Design apps?” QKSMS is ranked 7th while Atlas is ranked 71st. The most important reason people chose QKSMS is:
When a new sms is received, a window will pop up that has the message and allows answering it from there, without having to open the app. It can be dismissed by tapping anywhere else on the screen.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Built-in ad blocking
The browser uses EasyList data to remove ads from sites. It can further be supplemented with EasyPrivacy data to limit website ability to track you.
Pro Stores preferences on per-site basis
The browser can be set to remember which sites need to be shown in desktop mode, with certain content filtering settings, etc.
Pro Can browse two tabs at once
Atlas has a dual pane view that shows two pages side by side.
Pro Can be set to very low data usage
Pro Allows responding to SMS without opening the app
When a new sms is received, a window will pop up that has the message and allows answering it from there, without having to open the app. It can be dismissed by tapping anywhere else on the screen.

Pro Per-conversation notification settings
Users can set different notification settings per user as an easy way to know who is messaging without having to look at the actual message.

Pro Easily communicate with groups
Users can communicate with large groups at the same time due to the included group messaging feature. This is convenient when trying to synchronize with friends or colleagues.
Pro Very active developer who listens to the community
While QKSMS is one of the younger apps, the developer is quickly adding features/fixing bugs.
Pro Free
The app is available for free with an optional donation IAP that ranges from $1-$10.
Pro Beautiful design
Responsive, highly customizable Material Design interface makes for a native looking app that fits in well with Google's UI design guidelines.

Pro Save yourself from sending out bad messages
Through delayed messaging one can set it up so that a message is not sent automatically. This can help for those times that it may be best to think something over before sending out a rash message.
Pro Readable in day or night due to themes
There are light and dark themes available within the settings which can be switched depending on how light it is around one when using the app. The dark theme can also help to conserve battery when being used as not as much brightness and hence battery will be used.
Pro Schedule messages
Users can schedule messages to be sent for later.

Pro Convenient Android Wear support
Those that own an Android Wear device will be able to set it to receive their messages on the Android Wear device making for convenient notifications and easy messaging through not having to take their phone out.
Cons
Con Abandoned
Atlas was last updated on September 19, 2014.
Con Last update was 2021
Con Buggy
There are little annoyances here and there, from dark theme problems making text unreadable to crashing and missing notifications.
Con Lacks features compared to other offerings
