Chomp SMS is developed by Delicious Inc. who are also responsible for developing the BlackBerry Crunch SMS app and the iOS Bite SMS app. This free SMS app is feature-packed and is one of the best replacement SMS apps found within the Google Play Store. You'll get access to over 800+ Emojis, an SMS blocker/blacklist, SMS signatures (like email signatures), quick-reply pop ups, improved MMS & group messaging, and much more. You can also download or create custom themes to choose how your conversations appear.
Handcent SMS is another popular free option which brings full SMS and MMS support powered by the Handcent network. It features an integrated spell-checker, optional quick-reply, and advanced security options. You get full support of over 20 different language and can improve/export vCards straight through the app. Similar to Chomp, Handcent is highly customizable and there is a variety of pre-made templates to choose from.
Textra SMS is made by the same people as Chomp however, it is much more lightweight and does not include all the bells and whistles that Chomp is known for. If you are someone who has an older Android that is having issues with Chomp's performance or you simply don't need all the advanced features then Textra is will likely be an excellent choice for your needs.
Go SMS Pro
With over 50,000,000 installs, Go SMS Pro is one of the most downloaded SMS apps for Android and is also one of the highest reviewed. Featuring support for Emojis, MMS, group messaging, 200+ personalized themes, auto-reply, quick-reply pop ups, SMS blocking, and much more. This is an excellent choice for replacing the stock SMS app and is highly customizable to help suit your needs.
Hi SMS is one of the newer SMS apps found within Google Play so it does not have as large of a reputation as the others listed here. However, this app is the closest you'll get to the default iOS 7 messaging app. It includes support for MMS, resizable fonts, pop up quick-replies, SMS/MMS delivery reports, and much more. If you are switching from an iPhone to an Android and are looking to get the closest to an iOS experience then this app is for you.